Fluid delivery apparatus

ABSTRACT

An apparatus for accurately infusing medicinal agents into an ambulatory patient at specific rates over extended periods of time. The apparatus is of a compact, low profile, laminate construction and includes an elastic distendable membrane, which, in cooperation with a thin planar base, defines a fluid chamber having a fluid outlet. Disposed within the fluid chamber is a thin fluid permeable member which precisely controls the rate of fluid flow through the fluid outlet.

This is a continuation-in-part application of Ser. No. 07/367,304, filed Jun. 16, 1989, now U.S. Pat. No. 5,019,047.

BACKGROUND OF THE INVENTION

The present invention relates generally to fluid delivery devices. More particularly, the invention concerns an improved apparatus for infusing medicinal agents into an ambulatory patient at specific rates over extended periods of time.

DISCUSSION OF THE INVENTION

Many medicinal agents require an intravenous route for administration thus bypassing the digestive system and precluding degradation by the catalytic enzymes in the digestive tract and the liver. The use of more potent medications at elevated concentrations has also increased the need for accuracy in controlling the delivery of such drugs. The delivery device, while not an active pharmacologic agent, may enhance the activity of the drug by mediating its therapeutic effectiveness. Certain classes of new pharmacologic agents possess a very narrow range of therapeutic effectiveness, for instance, too small a dose results in no effect, while too great a dose results in toxic reaction.

In the past, prolonged infusion of fluids has generally been accomplished using gravity flow methods, which typically involve the use of intravenous administration sets and the familiar bottle suspended above the patient. Such methods are cumbersome, imprecise and require bed confinement of the patient. Periodic monitoring of the apparatus by the nurse or doctor is required to detect malfunctions of the infusion apparatus.

Devices from which liquid is expelled from a relatively thick-walled bladder by internal stresses within the distended bladder are well-known in the prior art. Such bladder, or "balloon" type, devices are described in U.S. Pat. No. 3,469,578, issued to Bierman and in U.S. Pat. No. 4,318,400, issued to Perry. The devices of the aforementioned patents also disclose the use of fluid flow restrictors external of the bladder for regulating the rate of fluid flow from the bladder.

The prior art bladder type infusion devices are not without drawbacks. Generally, because of the very nature of bladder or "balloon" configuration, the devices are unwieldly and are difficult and expensive to manufacture and use. Further, the devices are somewhat unreliable and their fluid discharge rates are frequently imprecise.

The apparatus of the present invention overcomes many of the drawbacks of the prior art by eliminating the bladder and making use of recently developed elastomeric films and similar materials, which, in cooperation with a, plate-like base defines a fluid chamber that contains the fluid which is to be dispensed. The elastomeric film membrane controllably forces fluid within the chamber into fluid flow channels provided in the base. In one form of the apparatus of the invention, a thin, planar shaped flow rate control member is strategically located within the chamber to precisely control the rate of flow of the liquid toward the fluid flow channels. The flow rate control member ca be very thin and can be selected to have a very precise degree of permeability so that the rate of flow of fluid into the fluid flow channels can be controlled with great accuracy.

The use of state of the art thin membranes and films permits the construction of compact, low profile, laminated structures which are easy to use and inexpensive to manufacture. When the devices of the invention are to be used with ambulatory patients they are constructed of flexible materials and are provided with a thin adhesive backing which permits the device to be conveniently self-affixed to the patient's arm or other parts of the body.

The apparatus of the invention can be used with minimal professional assistance in an alternate health care environment, such as the home. By way of example, devices of the invention can be used for the continuous infusion of antibiotics, hormones, steroids, blood clotting agents, analgesics, and like medicinal agents. Similarly, the devices can be used for I-V chemotherapy and can accurately deliver fluids to the patient in precisely the correct quantities and at extended microfusion rates over time.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an apparatus for expelling fluids at a precisely controlled rate which is of a compact, low profile, laminate construction. More particularly, it is an object of the invention to provide such an apparatus which can be used for the precise infusion of pharmaceutical fluids to an ambulatory patient at controlled rates over extended periods of time.

It is another object of the invention to provide an apparatus of the aforementioned character which is highly reliable and easy-to-use by lay persons in a non-hospital environment.

Another object of the invention is to provide an apparatus which can be factory prefilled with a wide variety of medicinal fluids or one which can readily be filled in the field shortly prior to use.

Another object of the invention is to provide an infusion device in which fluids can be delivered either at a fixed rate or at variable rates and one which is operational in all altitudes and attitudes.

Still another object of the invention is to provide an apparatus of the class described which is soft, conformable and compliant so as to readily conform to the patient's anatomy proximate the point of infusion.

Yet another object of the invention is to provide an apparatus as described in the preceding paragraph which is provided with a thin, flexible foam backing with adhesive for self-attachment. The apparatus can be unobtrusively worn under clothing.

A further object of the invention is to provide a low profile, fluid delivery device of laminate construction which can be manufactured inexpensively in large volume by automated machinery.

Another object of the invention is to provide a device of the character described in which fluid is dispelled from the apparatus through either an integral infusion needle, or through a luer type connector, by a thin, distendable membrane cooperatively associated with a thin, plate-like base.

Another object of the invention is to provide an apparatus of the aforementioned character in which the distendable member is permeable to gases at least in one direction, whereby gases within the medicinal agent can be released from the fluid chamber and not injected into the patient.

Still another object of the invention is to provide an apparatus as described in the preceding paragraphs in which the rate of fluid flow from the apparatus is precisely controlled by a thin planar shaped, fluid permeable member which forms a part of the low profile, laminate construction of the apparatus.

Another object of the invention is to provide a fluid delivery device embodying an iostropic distendable membrane with a uniform modulus of elasticity which cooperates with a base to define a fluid chamber having a fluid outlet in communication with dispensing port for dispensing fluid from the device and including a flow control element disposed intermediate the fluid outlet and the dispensing port.

Still another object of the invention is to provide a device as described in the preceding paragraph in which the flow control element comprises a restriction which controllably restricts the flow of fluid between the fluid outlet and the dispensing port.

A further object of the invention is to provide a fluid delivery device embodying a distendable membrane assembly which cooperates with a base to define a fluid chamber having a fluid outlet in which the distendable membrane assembly is of multilaminate construction being made up of a plurality of individual members or layers which cooperate to controllably urge fluid within the fluid chamber outwardly of the fluid outlet of the device.

Another object of the invention is to provide a fluid delivery device of the chamber described in the preceding para graph which includes a rate control membrane and in which the base is provided with a multiplicity of micro-channels for conducting fluid to the rate control membrane at precise rate over a predetermined active area.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a generally perspective view of one form of the fluid dispensing apparatus of the invention.

FIG. 2 is an exploded, generally perspective view of the apparatus of FIG. 1.

FIG. 3 is a top view of the apparatus partly broken away to show internal construction.

FIG. 4 is an enlarged cross sectional view taken along lines 4--4 of FIG. 3.

FIG. 5 is a cross sectional view taken along lines 5--5 of FIG. 4.

FIG. 6 is a fragmentary view taken along lines 6--6 of FIG. 4.

FIG. 7 is a cross sectional view taken along lines 7--7 of FIG. 4.

FIG. 8 is a view similar to FIG. 4, but illustrating the separation of the molded needle cover from the device.

FIG. 9 is a cross sectional view taken along lines 9--9 of FIG. 8.

FIG. 10 is a generally perspective exploded view of another embodiment of the fluid dispensing apparatus of the present invention.

FIG. 11 is a top view of the apparatus shown in FIG. 10.

FIG. 12 is a cross sectional view taken along lines 12--12 of FIG. 11.

FIG. 13 is a cross sectional view taken along lines 13--13 of FIG. 12.

FIG. 14 is a cross sectional view taken along lines 14--14 of FIG. 12.

FIG. 15 is a fragmentary view taken along lines 15--15 of FIG. 12.

FIG. 16 is a view similar to FIG. 12, but showing the molded needle cover separated from the device.

FIG. 17 is a greatly enlarged fragmentary view illustrating the method of fluid fill of the apparatus of this form of the invention.

FIG. 18 is a generally perspective exploded view of another embodiment of the apparatus of the present invention.

FIG. 19 is a fragmentary top view of the apparatus of this form of the invention.

FIG. 20 is a cross sectional view taken along lines 20--20 of FIG. 19

FIG. 21 is a cross sectional view taken along lines 20--20 of FIG. 19.

FIG. 22 is a generally perspective exploded view of still another form of the apparatus of the present invention.

FIG. 23 is a plan view of the apparatus of FIG. 22 partly broken away to show internal construction.

FIG. 24 is a greatly enlarged fragmentary perspective view of a portion of the apparatus illustrating the arrangement of the rate control membranes of the device.

FIG. 25 is a cross sectional view taken along lines 25--25 of FIG. 23.

FIG. 26 is a fragmentary view taken along lines 26--26 of FIG. 25.

FIG. 27 is a cross sectional view taken along lines 27--27 of FIG. 25.

FIG. 28 is a cross sectional view taken along lines 28--28 of FIG. 25.

FIG. 29 is a fragmentary, cross sectional view similar to FIG. 25, but showing the needle cover separated from the apparatus of the invention.

FIG. 30 is a generally prospective, exploded view of still another embodiment of the present invention.

FIG. 30A is a fragmentary plan view taken along lines 30A--30A of FIG. 32 showing the internal construction of the apparatus of FIG. 30.

FIG. 30B is an enlarged cross-sectional view of the circled area shown in FIG. 32.

FIG. 31 is a fragmentary, generally perspective view of the circled portion of the flow rate control membrane as shown in FIG. 30.

FIG. 32 is a cross-sectional view of the apparatus shown in FIG. 30.

FIG. 33 is an exploded, generally perspective view of still another form the apparatus of the invention.

FIG. 34 is a fragmentary plan view of the fluid outlet portion of the apparatus of FIG. 33, partly broken away to show internal construction.

FIG. 35 is a cross-sectional view taken along lines 35--35 of FIG. 34.

FIG. 36 is a cross-sectional view taken along lines 36--36 of FIG. 34.

FIG. 37 is a cross-sectional view taken along lines 37--37 of FIG. 36.

FIG. 38 is a fragmentary, generally perspective view of a portion of the flow control means of this form of the apparatus of the invention.

FIG. 39 is a fragmentary, generally perspective view of the distendable membrane of the latest form of the invention illustrating the laminate construction thereof.

DESCRIPTION OF THE INVENTION

Referring to the drawings and particularly to FIGS. 1 through 9, one embodiment of the apparatus for use in infusing medicinal fluids into a patient is there illustrated and generally designated by the numeral 12. As indicated in FIG. 1, the apparatus of this form of the invention comprises a laminate, or layered, structure made up of a plurality of thinplate-like components. As best seen by referring to FIG. 2, the apparatus comprises a thin, generally planar plate-like base 14, having a pair of flow rate control channels provided here as longitudinally extending fluidconduits 16 and 18. Conduits 16 and 18 are interconnected by a fluid transfer manifold, or transverse conduit 20, which, in turn, is interconnected with a fluid outlet passageway 22. A thin, generally planardistendable elastomeric membrane, or member, 24 cooperates with base 14 to form a chamber 25 (FIG. 4). Member 24 is distendable out of plane in the manner shown in FIG. 4 by the introduction of fluid into the chamber underpressure. As the distendable member 24 is distended by the fluid pressure, internal stresses are formed in the member which continuously urge it to return to its original planar configuration. The method of introduction offluids into chamber 25 will presently be described. As shown in FIG. 5, to maintain the low profile character of the device, the height of the fluid chamber is substantially less than the width of base 14.

Forming an important aspect of the apparatus of the invention is the provision of flow control means which is disposed internally of chamber 25for controlling the rate of fluid flow through the outlet 22 formed in basemember 14. In the embodiment of the invention hereshown, the flow control means is provided in the form of a thin, permeable member 26 which is superimposed over base 14 in the manner shown in FIG. 4. As will presentlybe described, member 26 precisely controls the rate of fluid flow from chamber 25 into fluid conduits 16, 18 and 20 formed in base 14. It is thisprecise control of the rate of fluid flow which enables infusion into the patient of medicinal fluids at an extremely precise rate over extended periods of time ranging from several hours to in excess of 24 hours depending on sized reservoir volume.

Superimposed over flow control member 26 is a distendable membrane engagement means. This means is here provided in the form of a generally planar member 28 having a peripheral portion 28a to which the margins of distendable member 24 are bonded, as by adhesive or thermo-bonding. Member28 also has a pair of longitudinally extending, spaced apart upstanding protruberances 30. Each of the protruberances 30 is provided with a longitudinally extending first fluid passageway or conduit 32. When the apparatus is assembled in the manner shown in FIG. 9, passageways 32 are superimposed over fluid conduits 16 and 18 and protruberances 30 extend upwardly into fluid chamber 26 so as to define ullage "U" within chamber 25. In operation of the device, a distendable membrane 24 attempts to return to its original planar configuration (FIG. 9), it will move toward engagement with the upper surfaces of protruberances 30 and in so doing will efficiently force the fluid contained within chamber 25 uniformly through the flow control member 26 and into passageway 16 and 18. The configuration of protuberances 30 ensure that all of the fluid within chamber 25 will be dispelled therefrom as the membrane returns toward its starting configuration. Passageways 16, 18, and 32 can be alternately configured to provide various degrees of fluid exposure to rate control membrane 26 whereby the active surface area of membrane 26 is increased ordecreased.

Superimposed over the assembly comprising base 14, distendable membrane 24,flow control member 26, and distendable membrane engaging member 28 is a porous plastic cover 34 which functions to provide a superstructure and a venting means for venting gases, if any, contained within the medicinal agent. Affixed to the top of cover 34 is a medicant and use instruction label 36 which can be used to identify the medicinal fluid contained within chamber 25 of the device.

Affixed to the bottom of base 14 is a cushioning means shown here as a thin, planar shaped foam pad 38. Foam pad 38 is provided with adhesive on both its upper and lower surfaces. The adhesive on the upper surface of pad 38 enables the pad to be affixed to the lower surface of base 14. As indicated in FIGS. 2 and 4, a peel strip 40 is connected to the bottom surface of foam pad 38 by the adhesive provided thereon. When the device is to be used, peel strip 40 can be stripped away from pad 38 so that the adhesive on the lower surface of the foam pad 38 can be used to releasablyaffix the apparatus of the invention to the anatomy of the patient.

Turning now to FIGS. 4 and 8, a needle assembly 42 is integrally formed with base 14. Needle assembly 42 which includes a distal portion 42a and aproximal portion 42b, is provided with a longitudinally extending bore 44. As best seen in FIG. 4, bore 44 is in communication with outlet passageway22 formed in base 14. Fixedly received within that portion of passageway 44, which extends through distal portion 42a, is a hollow infusion needle 46 of the character typically used for injecting fluids into a patient. The fluid outlet end of needle 46 is received within that portion of passageway 44 which extends through proximal portion 42b. Intermediate portions 42a and 42b is a reduced diameter frangible portion 42c which canbe broken so as to separate portions 42a and 42b to expose the outlet end of needle 46 in the manner shown in FIG. 8. Also forming a part of proximal portion 42b is a protective sheath 48 for encapsulating and protecting needle 46. Needle assembly 42 also includes web means for further assisting in securing and maintaining the needle in an appropriateinvasive position to preclude inter-vascular trauma. The web means are hereprovided as a soft, flexible butterfly assemblage 49, which, as shown in FIGS. 1 and 7, is integrally formed with base 14 and joined therewith by webbing 49a. Butterfly assembly 49 also provides appropriate surface area for tape adhesion covering the injection site.

Turning now to FIGS. 2, 3, 4 and 6, the distendable membrane engagement element 28 which comprises the means for creating an ullage within chamber25, also includes an upstanding transversely extending portion 50 having a fluid passageway 52 extending therethrough. In the present embodiment of the invention, the open end 52a of passageway 52 is closed by a closure member 54 which is adapted to sealably close passageway 52 after chamber 25 has been filled with the selected medicinal agent. Passageway 52 can also be closed by any suitable means such as thermal or mechanical sealing. As best seen by referring to FIG. 4, passageway 52 is in communication with a pair of longitudinally extending passageways 56 formed in element 28. Passageways 56 are, in turn, in communication with chamber 25 via passageways 58. As illustrated in FIG. 2, passageways 58 extend through protuberances 30 and are disposed in the ends of protuberances 30 located proximate transversely extending passageway 52.

The apparatus of this first embodiment of the invention is adapted to be filled with the selected medicinal fluid at time of manufacture. This is accomplished by removal of plug 54 so that fluid under pressure can be forced into passageway 52 and thence into chamber 25 via passageways 56 and 58. As the fluid under pressure flows through passageways 58, it will cause the membrane 24 to distend upwardly into initial engagement with cover 34 in the manner shown in FIG. 4. After chamber 25 has been filled with the medicinal fluid, closure plug 54 is bonded or otherwise affixed in place within the open end 52a of conduit 52 so as to seal chamber 25 with respect to atmosphere.

So long as needle assembly 42 remains intact in the manner shown in FIG. 4,the fluid will be retained within chamber 25. However, upon twisting and breaking the frangible section 42c so that portion 42b of the needle assembly can be removed as shown in FIG. 8, distendable membrane 24 will begin to expel fluid through the needle 46. The rate of expulsion of fluidis, of course, controlled by the permeable membrane 26 which is disposed intermediate the fluid flow passageways 32 of member 28 and fluid flow passageways 16 and 18 formed in base 14.

As previously mentioned, the state of the art materials used in the construction of the apparatus of the invention markedly contribute to the reliability, accuracy and manufacturability of the apparatus. Before discussing the alternate forms of the invention shown in the drawings, a brief review of the materials used in constructing the apparatus is in order.

With respect to the base 14, a wide variety of materials can be used, including; metals, rubber or plastics that are compatible with the liquidsthey contact and are preferably not non-allergenic. Examples of such materials are stainless steel, aluminum, latex rubber, butyl rubber, nitrile rubber, polyisiprene, styrene-butadiene copolymer, silicones, polyolefins such as polypropylene and polyethylene, polyesters, polyurethane, polyamides and polycarbonates. Manufacturers of suitable materials include; Dow Corning of Midland, Mich., General Electric of Schenectady, N.Y. and Shell Chemical Company of Houston, Tex., DuPont Chemical of Wilmington, Del., and Eastman Chemical of Kingsport, Tenn.

Considering next the important flow control means, or member 26, precision microflow through this important component is a pressure driven flow delivery process with controllable delivery rates between 0.1 to 4.5 milliliters per hour. Depending on the medicinal agent to be delivered andthe required flow rate regime, several microporous membranes can be employed, including asymmetric substrate based films such as cellulose acetate, cellulose acetate buterate, and ethyl cellulose. These membrane films may vary from 20 microns to 100 microns thick and can be made of a porous substrate with a controlled skin where the active porosity can varyfrom angstroms to 50 microns in diameter. Additionally, other acrylic resins can also be used for thin film, delivery membranes such as poly-methyl-methacrylate (PMM) and polysulfone on PVC also with approximately 2 microns thickness of skin of active membrane surface on upto 100 microns of substrate backing. Other matrix polymer systems are also candidates for microfilm membranes and include PCCE copolyesters and nylonPEBAX-polyethersteramide (PEEA), as well as PTFE, PVDF, P-P mixed ester cellulose and certain other polycarbonates. Manufacturers of these materials include; Bend Research (Cellulose Acetates, polysulfones), Eastman Chemical (PCCE Copolyester #9966), Atochem (PEBAX Nylon), Dupont (Hytrel), Rohm Pharmaceuticals (Acrylic Resins) and Millipore (PTFE), PVDFand mixed ester cellulose).

Considering next the elastic distendable membrane 24, this important component can be manufactured from several alternate materials including rubbers, plastics and other thermoplastic elastomers. These include latex rubber, polyisoprene (natural rubber), butyl rubber, nitrile rubber, otherhomopolymer, copolymers (random, alternating, block, graft, crosslink and starblock), mechanical poly-blends and interpenetrating polymer networks.

Examples of materials found particularly well suited for this application include; silicone polymers (polysiloxanes) (high performance silicone elastomers made from high molecular weight polymers with appropriate fillers added). These materials are castable into thin film membrances andhave high permeability (which allows maximum transport of vapor and gas), high bond and tear strength and excellent low temperature flexibility and radiation resistance. Additionally, silicone elastomers retain their properties over a wide range of temperature (-80° to 200° upto 2,000 lb./in² elongation up to 600%.

Further, silicone (polyorganosiloxanes) are thermally stable, hydrophobic organometallic polymers with the lowest P-P interaction (of all commercially available polymers. This fact coupled with the flexibility ofthe backbone results in a low Tg (-80° C.) and an amorphous rubbery structure for the high MW (polydimethylsiloxanes). Silicone rubber membranes are considerably more permeable to gases than membranes of any other polymer. Depending on the medicinal fluid used and the filling of the storage mode, which will determine the desired mass transport characteristics of the membrane (permeability and selectivity), other materials of choice include polyurethane-polysiloxane copolymers, blends and IPN's. By example, polydimethylsiloxane (PDMS) and polyurethane (PU) multicomponent IPN containing 10%-20% weight of PU shows enhanced initial modulus relative to that of PDMS itself.

Interpenetrating polymer networks (IPNS) are unique blends of cross-linked polymers containing essentially no covalent bonds, or grafts between them.True IPNS are also homogeneous mixtures of component polymers. Further examples of an additional candidate materials would be a polyurethanepolysiloxane (IPN) bilaminated with a polyparaxylene or alternately bilamination of polydimethylsiloxane (PDMS) and polyparaxylene. Coextruded laminates of this type can be selected according to the desired gas permeability for vapor and O₂, N₂ and CO₂ diffusion and their specific selectivity requirements as wellas for direction of gas migration when appropriately layered.

Manufacturers of materials suitable for use in the construction of the distendable membrane, include Dow Chemical, General Electric, B.P. Polymers, Mobay Chemical, Shell Oil Corp., Petrarch Systems, DuPont, Concept Polymers and Union Carbide Corp.

With respect to the structural cover 34, in certain embodiments of the invention, this component can be produced from one of several polymer groups. The plastic structure of this component typically contains an intricate network of open celled omni directional pores. The pores can be made in average sizes for 0.8 micron to 2,000 micron and, gives the porousplastic a unique combination of venting filtering, wicking and diffusing capability and structural strength. Further, the material is strong, lightweight, has a high degree of chemical resistance and depending on theparticular configuration of the apparatus, can be flexible. The degree of hardness can range from soft, resilient or rigid, and depending on the specific micro diameter range desired, the following polymers can be employed: Polypropylene(PP), Ultra high molecular weight polyethylene (UHMW PE), High density polyethylene (HDPE), Polyvinylidene Fluoride (PVDF), Ethylene-vinyl acetate (EVA), Styrene Acrylonitrile (SAN), Polytetrafluoroethylene (PTFF). A suitable source of these materials is Porex Technologies of Fairburn, Ga.

An alternate material for use in constructing the covers, as for example, covers 34 and 80, when the cover is to serve as a non-permeable gas barrier, is a material sold by B-P Chemicals International of Cleveland, Ohio, under the name and style "Barex". This material, which can also be used to alternately construct base 14 and element 28, is a clear rubber modified Acrylonitrile Copolymer which has wide application in the packaging industry because of its superior gas barrier, chemical resistance and extrusion (thermoforming) and injection molding capabilities. Structures using this material can be manufactured in eithermonolayer or coextrusion (with such other materials as polyethylene, polypropylene, polystyrene and other modified styrenes). Combinations of different materials can be used to enhance the desired physical propertiesof the thermoformed part.

Finally, the foam pad adhesive 38 and peel strip 40 is preferably composed of a thin (1/32") 30 mil closed cell polyethylene (PE) foam double coated with a non-sensitizing acrylic pressure sensitive adhesive (PSA), and 90 lb. white polyethylene coated release liner (peel strip). This foam is also available in 1/16 inch and 1/8 inch thickness. The foam is stretchable, soft, elastic, conformable, cushioning, hypoallergenic, and is desirable for application where sustained use is required. The materialis available from the 3M Company of Saint Paul, Minn. and from Betham Corporation of Middlesex, N.J.

Turning now to FIGS. 10 through 17, another embodiment of the invention is thereshown. The apparatus of this form of the invention is similar in manyrespects to that previously described and like numbers are used to identifylike components. Unlike the apparatus illustrated in FIGS. 1 through 9 which has a thermo sealed filling port, the apparatus of this second form of the invention is adapted to be filled using a hypodermic syringe. The device may have a cover made of the same material as cover 34, or may havea different type of impermeable cover, the function of which will presentlybe described.

Referring to FIG. 10, the apparatus can be seen to comprise a base 14, a distendable member 24 and a flow control member 26 all of which are of thesame general character and function in the same manner as in the earlier described embodiment of the invention. The distendable member engaging element 60 is of slightly different construction and includes filling means which enables chamber 25 to be filled using a hypodermic syringe andneedle of the character identified in FIG. 17 by the numeral 62. Element 60is superimposed over flow control member 26 and includes a pair of longitudinally extending, spaced apart upstanding protuberances 64. Each protuberance 64 is provided with fluid passageways 66 which communicate with fluid passageways 16 and 18 provided in base 14. Element 60 also includes an upstanding transversely extending portion 68 having a fluid passageway 70 extending therethrough (FIGS. 10, 11 and 17). In this secondembodiment of the invention, the open end 70a of passageway 70 is closed bya septum means for receiving a hypodermic needle. The septum means is here provided as a septum 72 which is adapted to sealably close the open end 70a of passageway 70. Septum 70 is constructed of a self-sealing, puncturable material such as silicone-SEBS (a composite incorporating a silicone interpenetrating network (IPN) into a styrene-ethylene butylene-styrene block copolymer). If desired, the earlier form of the apparatus of the invention as shown in FIGS. 1 through 9 can alternativelyhave a fill means such as shown in FIG. 17 to permit filling in the field. As best seen by referring to FIG. 12, passageway 70 is in communication with a pair of logitudinally extending passageways 74 formed in element 60. Passageways 74 are, in turn, in communication with chamber 25 via passageways 76.

Cover 80 is formed of a clear plastic material which is impermeable to fluid including gases. This type of cover is used when the medicinal agentwithin chamber 25 is such that it must be sealed with respect to atmosphere. As best seen in FIG. 10 cover 80 is provided with a pair of longitudinally extending protuberances 82 which are interconnected by a web 84. Web 84 carries on its upper surface an impermeable barrier peel strip 86 that covers vent means provided in web 84 to enable venting of chamber 25 at time of use.

The apparatus of this second form of the invention includes a needle assembly 42 of similar function and construction as that previously described and includes a shielded injection needle 46. The needle assemblyis provided with web means and a frangible section 42c to enable portion 42b of the needle assembly to be removed in the manner shown in FIG. 16.

As before, so long as needle assembly 42 remains intact in the manner shownin FIG. 12, the fluid will be retained within chamber 25. However, upon twisting off the frangible section 42c so that portion 42b on the needle assembly can be removed as shown in FIG. 16, distendable membrane 24 will begin to expel fluid through the needle 46. The rate of expulsion of fluidis, of course, controlled by the permeable membrane 26 which is disposed intermediate the fluid flow passageways 66 of member 60 and fluid flow passageways 16 and 18 formed in base 14.

Referring to FIGS. 18 through 21, another embodiment of the invention is thereshown. The apparatus of this form of the invention is similar in manyrespects to the embodiment shown in FIGS. 1 through 9 and like numbers are used to identify like components. Unlike the apparatus illustrated in FIGS. 1 through 9, the apparatus of this third form of the invention does not embody an injection needle assembly. Rather, the device of this embodiment includes a luer connector assembly 90, the function of which will presently be described.

Turning particularly to FIG. 18, the apparatus can be seen to comprise a base 14, and an operating assembly 92 associated therewith comprising a distendable member 24, a distendable member engaging element 28, a flow control member 26 and a cover 34, all of which are of the same general character and function in the same manner as the embodiment of the invention shown in FIGS. 1 through 9. The device also includes an adhesivefoam pad 38 and a peel strip 40 carried by base 14.

The luer connector assembly 90, which comprises the distinguishing feature of this form of the invention, is integrally formed with base 14 and includes a distal portion 90a and a proximal portion 90b. Distal portion 90a is provided with a longitudinally extending bore 94 which communicateswith outlet 22 of base 14. Comprising the proximal portion 90b of assembly 90 is a luer connector of standard construction having a fluid passageway 96 which communicates with bore 94 of distal portion 90a. The outlet of passageway 96 is sealed by a frangible closure which is removable to activate fluid flow. The outboard end of distal portion 90a, designated inthe drawings as 90c is of reduced diameter and is readily flexed to permit easy connection of the luer connector "L" with an external system "E" (FIG. 20).

As shown in FIGS. 18 and 21, base 14 includes fluid conduits 16, 18 and 20 which communicate with outlet passageway 22. Distendable membrane 24 functions to expel fluid from chamber 25, through flow rate control member26 and outwardly through outlet passageway 22 in the manner previously described.

Referring to FIGS. 22 through 29 yet another form of the invention is shownand identified by the numeral 100. For certain medicinal agents, it is desirable to provide an initial high rate delivery followed by a slower rate sustained delivery. This form of the invention permits this to be accomplished. The apparatus of this form of the invention is similar in many respects to the embodiment shown in FIGS. 1 through 9 and like numbers are used to identify like components. Unlike the apparatus illustrated in FIGS. 1 through 9, the apparatus of this fourth form of theinvention is not limited to a fixed rate infusion of the medicinal agent. Rather, because of the novel configuration of the distendable membrane engaging element and the dual flow rate control members of this form of the invention, a controlled variable rate of fluid flow is possible.

As best seen in FIGS. 22, 23 and 24, the apparatus of this last form of theinvention also comprises a laminate, or layered, structure made up of a plurality of thin plate-like components. The apparatus includes a thin, generally planar plate-like base 102, having a transverse recess 104 in communication with a fluid outlet passageway 106. A thin, generally planarelastic distendable membrane, or member 108 cooperates with base 102 to form a pair of discrete chambers 110 and 111 (FIG. 27). For certain applications, Chambers 110 and 111 may be of different individual size andconfiguration each having different volumes. As before, member 108 is distendable out of plane in the manner shown in FIG. 25 by the introduction of fluid into the chambers under pressure. The method of introduction of fluids into chambers 110 and 111 will presently be described.

Forming an important aspect of the apparatus of this fourth form of the invention is the provision of flow control means which are disposed internally of chambers 100 and 111 for controlling the rate of fluid flow of fluid from each chamber through outlet 106. In the embodiment of the invention hereshown, the flow control means is provided in the form of a flow rate control assembly 112 which is received within recess 104 formed in base 102 in the manner shown in FIGS. 22 and 24. Flow rate control assembly 112 includes a pair of permeable members 114 and 116 which, as will presently be described, precisely control the rate of fluid flow fromchambers 110 and 111 into fluid outlet 106. Passageway 106 is in communication with the fluid passageway of needle assembly 42 which is of the same construction as previously described herein.

As best seen in FIG. 24, assembly 112 comprises a manifold member 118 whichis closely receivable within recess 104 formed in base 102. Member 118 is provided with an internal fluid conduit 120 having fluid inlets 122 and 124 at either end and a fluid outlet 126 proximate its center. Outlet 126 is adapted to communicate with outlet passageway 106 provided in base 102 when member 118 is in position within recess 104. Permeable members 114 and 116 overlay inlets 122 and 124 and, in a manner presently described, control the flow of fluid into these outlets from chambers 110 and 111. Fluid inlets 122 and 124, can be constructed in various geometries and, incooperation with the ullage means, presently to be described, to provide various degrees of active surface area of the rate control membrane.

The distendable member engaging element 130 of this latter form of the invention is of slightly different construction and includes filling meanswhich enable chambers 110 and 111 to be filled separately. As best seen in FIGS. 22 and 25, element 130 is superimposed over base 102 and flow control assembly 112 and includes a pair of longitudinally extending, spaced apart upstanding protuberances 132 and 134. Protuberances 132 and 134 are provided with fluid passageways 136 and 138 respectively. Passageway 136 communicates with fluid inlet 122 and passageway 138 communicates with inlet 124 of assembly 112. By varying the configuration of these passageways and fluid inlets alternate active surface areas of the flow control membrane can be exposed. Element 130 also includes an upstanding transversely extending portion 140 having a pair of fluid passageways 142 and 144 extending from the open ends 142a and 144a thereof. As shown in FIG. 23, passageway 142 is in communication with passageway 136 of element 130 via a passageway 152 and passageway 144 is in communication with passageway 138 of element 130 via a passageway 148. Passageways 146 and 148, in turn, communicate with chambers 110 and 111, respectively, via passageways 150 and 152 respectively (see FIGS. 25 and 26). Open ends 142a and 144a of passageways 142 and 144 are closed by any suitable means such as heat sealing.

The apparatus of this fourth embodiment of the invention is adapted to be filled with the selected medicinal fluid at time of manufacture. This is accomplished by forcing fluid under pressure into passageways 142 and 144,and thence, into chambers 110 and 111 via passageways 150 and 152. As the fluid under pressure flows into the two chambers, it will cause the membrane 108 to distend upwardly into engagement with cover 34 in the manner shown in FIG. 27. After chambers 110 and 111 have been filled with the selected medicinal fluid, passageways 142 and 144 are sealably closed.Cosmetic closure plugs 154 and 156 can be used if desired at the ends of conduits 142 and 144. It is to be observed that membrane 108 is bonded along its margins 108a to member 130 and is in sealable engagement along its longitudinal center line with member 130 intermediate protuberances 132 and 134. With this construction, chambers 110 and 111 are maintained independent from one another.

Upon twisting off the frangible section 42c so that portion 42b on the needle assembly can be removed as shown in FIG. 29, elastic distendable membrane 108 will begin to expel fluid through flow control members 114 and 16. The rate of flow of fluid is, of course, controlled by the degree of permeability of each of the members 114 and 116. If one of these members has a greater permeability than the other, fluid will flow throughthat member at a greater rate. Accordingly, by varying the permeability of members 114 and 116, and with the output summed via flow channels 120 and 106, a larger initial volume of fluid can be injected into the patient. Continuous injection of fluid at a slower controlled rate will then follow. For example, if member 114 has a high degree of permeability, fluid will be forced out of chamber 110 at a rapid rate. On the other hand, if member 116 has a low permeability, fluid will be forced out of chamber 111 at a slower rate. With this arrangement, fluid can be simultaneously injected initially at a high rate from chambers 110 and 111then at a much slower rate from chamber 111.

As indicated in FIG. 22, the apparatus is closed by a cover 34 having a medicant label 36. If a barrier cover and base configuration is used, cover vent means as previously described, must be provided. Affixed to thebottom of the base is an adhesive foam pad 38 and a peel strip 40 so that the apparatus can be self-attached to the patient.

Turning now to FIGS. 30, 31, and 32, another embodiment of the apparatus for use in infusing medicinal fluids into a patient is there illustrated and generally designated by the numeral 200. The device of this form of the invention is similar in many respects to that shown in FIGS. 18 through 21 and like numbers are used to identify like components. As best seen by referring to FIG. 30, the apparatus comprises a thin, generally planar plate-like base 202 having at least one flow rate control channel. In the form of the invention shown in FIGS. 30 and 30A, the base is shown as having a pair of flow rate control channels provided here as longitudinally extending fluid conduits 204 and 206. Conduits 204 and 206 are interconnected by a fluid transfer manifold, or transverse conduit 208, which, in turn, is interconnected with a fluid outlet passageway. Distendable membrane engagement means, shown here as protuberances 209, perform the same function as protuberances 30 previously described. It is to be understood that in some applications only a single protuberance is provided and in other applications no protuberance at all is required.

A thin, initially generally planar distendable elastomeric membrane, or member, 24 (FIG. 32) cooperates with base 202 to form a chamber 25 (FIG. 32). Member 24 is distendable in the manner shown in FIG. 32 by the introduction of fluid into the chamber under pressure. As previously described herein, as the distendable member 24 is distended by the fluid pressure, internal stresses are formed in the member which continuously urge it toward engagement with protuberances 209 as it trys to return to its original configuration. The method of introduction of fluids into chamber 25 is as previously described in connection with the embodiment ofFIGS. 12 through 21.

An important feature of this latter embodiment of the invention is the provision of a multiplicity of flow rate control micro-channels 210 in base 202. Micro-channels 210 are disposed on either side of conduits 204 and 206 and communicate therewith via flow control means of a character presently to be described.

In the embodiment of the invention shown in FIGS. 30 through 32, the flow control means is provided in the form of a thin, multilayered or gradiatedassembly 212 which is superimposed over channels 210 in the manner shown inFIG. 32. With this construction, when the device is in a fluid discharge mode, fluid within chamber 25 is forced by membrane 24 through channels 213 provided in protuberances 30, through assembly 212, through micro-channels 210, into conduits 204 and 206 and outwardly through outletpassageway 214. Passageway 214 is connected with dispensing means shown here as luer connection assembly 90 which includes a fluid flow conduit and fluid dispensing port or luer connector "L". By controlling the area of the micro-channels, the active surface area of membrane assembly 212 which is exposed to fluid can be varied in a manner to optimize fluid flowthrough assembly 212. Similarly by controlling the size and shape of the micro-channels, the rate of flow of the fluid through membrane assembly 212 can also be uniformly maintained.

As indicated in FIG. 31, the flow control means of this form of the invention, rather than consisting of a single layer of a permiable material having the desired fluid flow characteristics, here comprises an assemblage of a plurality of layers of permiable materials, P-1, P-2, and P-3, each having selected characteristics. These layers, which may be composites, thin films, or porous substrates, may be constructed of any ofthe materials previously described herein so that the fluid pressure flow characteristics of the assemblage can be optimized for the particular medicinal or other fluid being dispensed. For example, layer P-1 may comprise an asymmetric membrane, or film, having a first porosity, P-2 maycomprise a resin membrane or film having a second porosity and layer P-3 may comprise a carrier substrate of predetermined porosity. In another application P-1 and P-3 may take the form of carrier substrates and P-2 may comprise a very thin, rate control element. In this way a unique composite, sandwich-like assemblage can be constructed. In certain applications assembly 212 can be constructed with gradient layers rather than with discrete elements in a manner to produce comparable results.

The multilayered, or gradient layer construction described in the precedingparagraph permits easier, thin-film manufacture, precise flow control over extended periods and easier handling of the membrane film during system manufacture.

Referring next to FIGS. 33 through 39, still another embodiment of the present invention is there shown. This embodiment of the invention is alsosimilar to that shown in FIGS. 18 through 21 and like numerals are used to identify like components. As best seen in FIG. 33, the device comprises a base 300 having a pair of flow rate control channels 302 and 304 and a transversely extending fluid transfer manifold conduit 306. Conduit 306 isconnected with an outlet 300 (FIG. 34) which, in turn, is in communication with a fluid dispensing means, shown here as a fluid dispensing port 312.

Unlike the embodiments of the invention previously described, the device ofthis form of the invention does not include a flow rate control membrane ofthe character previously described. Rather, the rate of fluid flowing from the dispensing means of the device is controlled by flow control means disposed intermediate outlet 310 and fluid dispensing port 312. The flow rate control means is here provided as a fluid flow micro-conduit 314 and a porous member 316 (FIG. 36) which functions to restrict the flow of fluid between outlet 310 and dispensing port 312.

Another critical difference between the embodiment of the invention now being considered and the previously described embodiments resides in the unique character of the stored energy means used for discharging fluid from the device. Here the stored energy means, rather than being a single isotropic, elastomeric distendable membrane, comprises a laminate assemblage made up of a plurality of initially generally planar distendable elements or films. Referring particularly to FIG. 39, the stored energy means is there shown as a laminate assemblage 318 made up ofindividual elements or membranes 320, 322, 324, 326 and 328. Assemblage 318functions in much the same way as the earlier described distendable membranes, and uniformly cooperates with base 300 to define fluid chambersor reservoirs 25. However, by constructing the stored energy means from a composite of several distinct elements or layers, the elastic characteristics of the stored energy means can be precisely tailored and the stored energy means can be uniquely constructed to function also as a gas permeability valve as well as the means for expelling fluids from the fluid reservoir. This unique, multilayered or gradient construction permits venting to atmosphere through the membrane surface certain selected, entrained gases or vapors in the reservoir while simultaneously precluding any negative migration of selected atmospheric gases or vapors into the reservior. Where the composite is made up of two or more layers of alternating thickness and premeability, and the permeability constants of the individual film layers are pressure dependent, the permeability of the stored energy means is effected and the direction of flow of the permiant through the membrane wall is controlled by the order in which theindividual layers or gradiations of the composite are assembled.

For example, referring to FIG. 39, layer 320 which may be distal to the reservoir comprises a thin film elastomer of a first thickness and a firstpermeability. On the other hand, layer 328, which may be proximal to the reservoir, comprises a thin elastomer film of a second thickness and a second permeability. Layers 322, 324 and 326 may be of further alternatingthickness and permeability and, if desired, may also have different perm-select characteristics. The selective arrangement of the different films each with its own individual permeability constants in ascending order, will dictate the direction of flow of selected gases and vapors through the stored energy means.

Having now described the invention in detail in accordance with the requirements of the patent statutes, those skilled in this art will have no difficulty in making changes and modifications in the individual parts or their relative assembly in order to meet specific requirements or conditions. Such changes and modifications may be made without departing from the scope and spirit of the invention, as set forth in the following claims. 

I claim:
 1. A device for use in infusing medicinal fluids into a patient at a controlled rate comprising:(a) a base having a width; (b) energy storage means for forming, in conjunction with said base, a fluid chamber having an outlet and a height substantially less than said width of said base, said energy storage means comprising at least one distendable member superimposed over said base, said member being distendable, as a result of direct pressural contact with the fluids to be infused, to establish internal stresses, said stresses tending to return said member to a less distended configuration; and (c) dispensing means operably associated with said outlet for dispensing fluid from the device.
 2. A device for expelling fluids at a controlled rate, comprising:(a) a base having a width; (b) an energy storage means comprising at lease one distendable member constructed from an elastic material, said energy storage means being adapted to be fitted over said base to form a fluid chamber having a height substantially less than the width of the base and having a fluid outlet, said distendable member being distendable by direct contact with the fluids to be dispelled, which are introduced into said fluid chamber under pressure, to establish stresses tending to uniformly urge said member toward a less distended configuration; and (c) dispensing means in communication with said fluid outlet for dispensing fluid from the device.
 3. A device as defined in claim 2 further including flow control means disposed intermediate said fluid outlet and said dispensing means for controlling the rate of flow of fluid from the device.
 4. A device for expelling fluids at a controlled rate, comprising:(a) a generally plate-like base; (b) a stored energy means comprising at least one distendable membrane constructed of an elastic material cooperating with said base to form a chamber having a fluid outlet, said distendable membrane being distendable by pressure exerted on said membrane by the fluids to be dispelled acting directly thereon to establish internal stresses tending to cause said membrane to move toward a less distended configuration; (c) dispensing means operably associated with said fluid outlet for dispensing fluids from said device; (d) flow control means disposed intermediate said fluid outlet and said dispensing means for controlling the rate of flow of fluid from the device.
 5. A device as defined in claim 4 in which said distendable membrane includes edge portions disposed proximate said base.
 6. A device as defined in claim 4 in which said base has a width and in which said chamber has a height substantially less than the width of said base.
 7. A device for use in infusing medicinal fluids into a patient at a controlled rate comprising:(a) a base having a width; (b) energy storage means for forming, in conjunction with said base, a fluid chamber having an outlet and a height substantially less than said width of said base, said energy storage means comprising a distendable member comprising a plurality of thin elastic membranes superimposed over said base, said member being distendable to establish internal stresses, said stresses tending to return said member to less distended configuration; and (c) dispensing means operably associated with said outlet for dispensing fluid from the device.
 8. A device as defined in claim 7 in which at least one of said elastic membranes is permeable to gas.
 9. A device as defined in claim 7 in which said membranes are bonded together to form a laminate construction.
 10. A device foe expelling fluids at a controlled rate, comprising:(a) a base having a width; (b) an energy storage means comprising a plurality of distendable members at least one of which comprises a thin membrane having a first permeability constant and at least one of which is constructed from an elastic material, said energy storage means being adapted to be fitted over said base to form a fluid chamber having a height substantially less than the width of the base and having a fluid outlet, said distendable members being distendable to establish stresses tending to uniformly urge said members toward a less distended configuration; and (c) dispensing means in communication with said fluid outlet for dispensing fluid from the device.
 11. A device as defined in claim 10 in which at least one of said distendable members comprises a membrane having a second permeability constant.
 12. A device as defined in claim 11 in which at least one of said distendable members comprises a membrane having a third permeability constant.
 13. A device for expelling fluids at a controlled rate, comprising;(a) a base; (b) a stored energy means comprising at least one distendable membrane constructed of an elastic material cooperating with said base to form a chamber having a fluid outlet; (c) dispensing means operably associated with said fluid outlet for dispensing fluids from said device; (d) first flow control means disposed internally of said chamber for controlling the rate of flow of fluid through said outlet, said first flow control means comprising at least one thin permeable member superimposed over said base; and (e) second flow control means disposed intermediate said fluid outlet and said dispensing means for controlling the rate of flow of fluid from the device.
 14. A device as defined in claim 13 further including distendable membrane engagement means, disposed intermediate said distendable membrane and said first flow control means, for engagement with said distendable membrane.
 15. A device as defined in claim 13 in which said base is generally plate-like in configuration, having at least one fluid flow channel formed therein for conducting fluid toward said fluid outlet.
 16. A device as defined in claim 15 in which said dispensing means includes a fluid dispensing port and in which said second flow control means controls the rate of flow of fluid through said fluid dispensing port.
 17. A device as defined in claim 16 in which said second flow control means comprises a fluid flow conduit which restricts the flow of fluid between said fluid outlet and said fluid dispensing port.
 18. A device as defined in claim 16 in which said second flow control means comprises a porous member disposed intermediate said fluid outlet and said fluid dispensing port.
 19. A device as defined in claim 16 in which said first flow control means comprises an assemblage comprising a plurality of generally planar-shaped permeable members. 